This invention relates to a cylindrical, blow-molded lidded barrel=wide-mouthed drum with a barrel lid and tension-ring closure, in which in the closed position, the tension ring, which is U-shaped in cross section, engages with its upper leg over the outside upper edge of the lid and engages with its lower leg under an outside edge of the barrel that runs basically horizontally or slightly obliquely downward in the opening area of the body of the barrel.
Such a lidded barrel is known from, e.g., DE-B-41 08 606. In the case of this barrel, however, the tension-ring closure is arranged some distance below the upper edge of the lid or the opening of the barrel, so that handling such a filled, e.g., 220-liter lidded barrel with a shipping weight of about 230 kg is possible only using special barrel-gripping tools. This type of a lidded barrel was developed by Mauser in 1975 and distributed worldwide under the designation "standard lidded barrel"; it is well-suited for handling solid, particulate or pasty contents, but such a barrel is not readily suited for use with liquids.
In the case of lidded barrels, the sealing action of the barrel lid on the barrel mouth is produced by bringing about axial prestressing on the lid seal via the tension ring leg bevels at the upper edge of the lid and at the outer border of the barrel body (or indentation) as the tension ring is clamped or closed.
On lidded barrels that are approved for use in, e.g., the chemical industry, certain requirements with respect to their storage and transport safety are set; compliance with these requirements is tested and examined in special acceptance tests (e.g., dropping on its side=jacket dropping, diagonal dropping on the edge of the lid, static internal pressure test, i.a.). In the case of known existing plastic lidded barrels, even when barrels are dropped from heights of about 1.20 m--e.g., from the bed of a truck--leaks occur, especially in the case of liquids, or complete detachment of the barrel lid can even occur.
The drawbacks of previously known lidded barrels consist of, especially,
a) when there is axial internal pressure on the barrel lid (surge pressure when a barrel filled with water is dropped on its jacket or when there is hydraulic internal pressure in a closed barrel), PA1 b) when a closed barrel that is filled with water slams flat against a side wall (jacket dropping), and PA1 c) when a closed barrel that is filled with water drops diagonally onto the edge of the lid, various reactions occur: PA1 the barrel lid is pressed axially outward, PA1 the tension ring is pulled axially outward, PA1 the tension ring (together with lid and barrel mouth area) is flattened at the central impact point, PA1 the tension ring is heavily buckled laterally at the impact point and its U-shape is flared at both buckling points, PA1 the lid edge tries to slide out from under the upper tension ring leg, PA1 prestressing on the seal is reduced and the locking system begins leaking. PA1 directly behind the outer lid edge, which is overlapped by the upper leg of the tension-ring closure and which is shaped in cross section like a downward-facing U, in which the lid seal is inserted or foamed-in, the barrel lid has an essentially V-shaped engaging groove which has a flat groove floor and which is drawn in peripherally downward into the barrel body, between a reduced-diameter central lid disk and the lid edge, PA1 the inside boundary of the engaging groove is formed by a ring part which slopes conically upward and to which is connected the flat lid disk with at least one bunghole that is recessed laterally in a bung housing, PA1 the lower leg of the tension-spring closure engages tightly below (about 15 mm) the upper barrel edge in an indentation in the upper barrel wall, whose upper boundary represents the essentially horizontal barrel edge or slightly oblique attachment surface for the tension ring and whose outline, as it moves downward toward the transition to the fully cylindrical part of the barrel wall, is essentially designed to be increasingly flat-conical, and PA1 the transition from the conical area to the fully cylindrical part of the barrel body is arranged at a distance of 80 mm to 140 mm, preferably about 120 mm, from the upper front edge of the barrel mouth edge, and PA1 the upper barrel edge of the barrel mouth is designed solidly as an outer support for a lid seal and has a width (thickness) of approximately double the wall thickness of the barrel body.
The stresses that occur with the deformations must be absorbed in each case by the U-shaped tension ring. In this connection, the legs are pressed outward (flared) in the buckling areas. If the stress on the legs is too high, it leads to permanent deformations, prestressing on the seal is reduced at those points, and significant flaring results in leaks or leaking of the barrel.
An attempt is thus to be made to reduce the deformation of the tension ring, especially the flaring in the U-area, by structural measures, especially in the barrel mouth area, at the barrel lid and/or tension ring, while at the same time continuing to ensure good handling, i.e., easy closing of the tension ring.